MZ-80b FI/O to HxC Cable

psmart
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Re: MZ-80b FI/O to HxC Cable

Post by psmart »

Good to know, keep us updated should anything else arise. Always a concern with a new board/components, it worked well for the +hour I tested it in both the MZ-800/MZ-2000 but that is no guarantee especially as the buffer chips around the Z80 degrade over time and the timing goes a little awry (which I found out on my RFS board when it worked perfectly in my machine but in another guys it didn't, software drivers had to be adjusted to compensate).

I normally like to get machines pristine and strip them down and clean all the circuits/replace caps, clean up the plastic etc, but the MZ-80B isn't plastic, rather painted/coated metal, so not sure what the procedure would be to get a machine back to the condition like yours is in, perfect condition.

I have to recap an MZ-2000 monitor this week, the vertical driver circuit has failed so got a new vertical driver IC and all the caps and if successful will do the same to my MZ-80A as it has a bit of a vertical size restriction, capacitors again! You may need to do the same.
Sharp MZ/X Series Projects and FPGA Emulator
engineers@work : https://eaw.app/sharpmz-series/
arnuphis
Posts: 43
Joined: Fri Jul 31, 2020 4:18 pm

Re: MZ-80b FI/O to HxC Cable

Post by arnuphis »

I recapped my power supply a while back. I will probably look at the Monitor board next once the component supplies pick up. I have been waiting 6 months for parts for my spare mac SE/30 power/flyback board. Thank you covid.

I have a spare MZ-80 while is one I use for supplies as its in a rough cosmetic condition. I will check the tube on that one as well just in case its the tube itself that is getting old in my main machine as opposed to it being a cap/convergence issue.

Now I need to get my hand on some of the games. I saw there was a pac man clone and a space invaders clone but I have yet to see them in any .dsk format. Maybe they were tape only?

Now the system seems stable I can actually start working on some programs for it.
psmart
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Re: MZ-80b FI/O to HxC Cable

Post by psmart »

One of the things which is needed is a disk to tape copy utility, that way it is easy to regenerate the cassettes. I tried to get the PC program on original.sharpmz.org running on a T30 to generate 80B/2000 cassettes but wasted a day with no success, guess you need an AT or 386 for it!
Sharp MZ/X Series Projects and FPGA Emulator
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arnuphis
Posts: 43
Joined: Fri Jul 31, 2020 4:18 pm

Re: MZ-80b FI/O to HxC Cable

Post by arnuphis »

Figures. I cleared out my PC Stuff so all I have is modern machines. I guess a trip to the thrift store may be in order. Ebay prices are nuts for 386s.
psmart
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Re: MZ-80b FI/O to HxC Cable

Post by psmart »

If you can lock the PC to a fixed speed then the assembler source code (provided) can be modified - it is supposed to use the 8254 timer but on the scope the marks/spaces were quite a bit out, ie 390uS instead of 366uS and the scope was dancing, even on the lead in, it couldn't get a fixed sync (had to manual trigger) so Im guessing the speed step was interfering. I tried to adjust the tracking speed of the tape drive to compensate for the timing difference and got it to read the header but the main program always had a CRC error. I also found the tape quality was important, old 'computer cassettes' didn't cut it, had to be a new TDK or the original sharp tapes (used the blank B side of the MZ-2000 application tape).

I plan to modify my RFS board software on the MZ-80A to write at 1800 baud, the source for the read is in the MZ-80B IPL but not the source for write albeit looks very similar, apart from timing delays and header pulse count, to the MZ-700 code. Another task!!!
Sharp MZ/X Series Projects and FPGA Emulator
engineers@work : https://eaw.app/sharpmz-series/
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